Water utilities in many parts of the world are facing growing challenges in their attempts to meet the demand for drinking water. This is due to a number of factors like climate change, extended periods of drought, population growth, migration and temperature rise which are exerting increasing pressure on existing water supplies. Another key factor is the leakage from water transmission and distribution networks. Leakage occurs due to deterioration and damage of networks and constitutes a major portion of water loss in water supply networks. Thus, the reduction of leakage from the water supply system is a vital strategy in the improvement of sustainable use of water.
A leak in a water supply pipe generates a sound which travels (in both upstream and downstream directions) along the water column inside pipe and the pipe shell, and the soil surrounding the pipe. This sound is commonly referred to as a leak signal, which comprises both acoustic and vibrational signals. It can be detected using acoustic leak detection equipment such as listening sticks and correlators; commonly used by the water industry. The distance up to which these leak signals can be detected depends upon the characteristics of pipe. In recent years, pipes of plastics such as MDPE have been increasingly favoured over older pipe materials such as metal (cast iron, etc) and concrete due to their lower rate of deterioration when in service. The sound caused by a leaking pipe is highly attenuated in pipes of plastics, particularly MDPE. Accordingly, it is very difficult to detect and locate water leaks in pipes of plastics such as polyethylene using currently available acoustic emission detection systems.
The accurate location of leaks is particularly important as it is expensive in terms of time, cost and physical efforts involved to find a leak, due to the excavation required to reach underground pipes.